Electric fuse



July`24, '1923. i 1,462,489

E. J. GRIGSBY ELECTRIC FUSE Filed Jan. 22 1918 Petente Juiy Zei, i

filed To all whom i? may :cm/wein Be it known that il, J. Genese?,

e citizen the United States, anni e resident of Chicago, in the eeunty o @ook and State e of liinois, have invented. eeitein new useui ilmpi'oveinents in Eleetiie Fuses;

ii fio hereby deeiei'e following is full, deer, end exeet deseiiptien then reference being ned to eeeonine i drawings, end to the cheieeteis of ie manned thereon, which oiin el' speeieetion This invention i'eietes 'to improvements electrical 'thermei nses which ene designed open circuits in which the fuses are connectedi upon the .passage of en ebnoiinei @wie thiough the qiienit; the `inse einnmei link or element which is mede oi such enenecter end such ci'oss section es to bieei down oi fuse et e, pedeteimined overleed Among the objects is to pioiiide, in e fuse of this character, ineens oi sensing e quick ruptuie of the fuse eienient when seiQn tened by the temperature oi' e pneetei-inined load current so es te eeet e moment out of the circuit end to pievent reestebiisiinent of the circuit thi-ongle parte of e jinse eiennent which has been impeiiectly iuptuifed.

fni'thei object of the invention is produce en improved enclosed inse o' that kind in Whichthe inse eienie;y is enclose/5 in and protected Toy e eoveiing, ne i5 known es e ceitiidge, the impioveinei this phase of the invention *gelatin te for preventing injury to the eeitiidge gases generated therein, eine to im of the fuse eiement undei heet. The invention consists end eri'engement of the drawings and ciesciioeci and is pointed ont in the anpe# l iin sei drawings, "Eigene l is seetion fuse eii'foodyy e; my invention,

thereby.

Figure 2 is emes 2--2 of Figuie L Figsiies 3 A" mili):

wie,

We is e eioss section ene ne 6 is en exiei Section snowing n the censtinetion i 'gene l the dmwings, l@ eesignetes e, fuse eeftiioge which eoinpiieee e c yiinicai shell; mede of any sniteieie insulating eteniei il, design eeps ei enemies which on ends ov: die shell 1G. "n

be sented in tice eeiininei eiip" Jente menne-i 'to ig be nels "i5 fee connection to the line eiitiies oi: enti eens M, mede of eiiiient conducting es biess ei coppe?, end are ineinoiel n cii'cuix; to the i nk l@ Within the sie eeitiidge lil the eonstiiietion shown in fe l, one of the link is een nected by eenen il diiee'tiy to the of eni'nie ll., otiiei* en@ ef the ei easing or sii-eil is i conducting, en bushing W- e., eioseiy Wit1 'n e sheii oi' eeft-Moige hes its. enten eniL e Teeiini i@ which ie eonined ne Je oi need o' neigneent een or end @i siieii i@ @then en@ seid iousnin Weicily f opening' through Wiiieo. ini-t 16 extends. Seated is e die@ 2 metile o' enge et' siionielei between said disc and the flange or shoulder 20, said spring tends to force the disc sway trom said flange and exerts a pulling stress on the fuse link. This pulling stress is constent, and it serves, when the tuse link is ruptured to quickly separate the parts of seid link at the sides ot the rupture. This quick andl eiiective separation of the parts of the -fuse link serves to promptly open the circuit and to reduce to a minimum the time in which the Jfuse element or link is' subjected to the fusing temperature; it 'beingapparent when the circuit is opened the thermal etlect ot the overload is arrested, Therefore. the prompt opening of the circuit .at the sides of the rupture hss the effect ot lessenin'g the accumulation ot gases in the fuse chamber ot the shell or cartridge due to theA :fusingya of the metal. it will be observed moreover that ss soon as the parts ot the fuse link are separated at the sides of the point of rupture thespring 22., in torcthe disc 2l away troni the tienne 20. has he ot increasing` the yolnininsl canf. LA,

.as does the opening et pucity of shell so as to thereby reduce any pressure which has accumulated theredue to-the generation ot gases.

feature et the construction described to .e observed is that the opening; in the terminal disc 2l., lbest shown suclisize and shape es to t i niine the cross section ot the 'fuse element which niay be used in the device. That is to say, the opening is of a size to perinit the passage therethrough of s. fuse eleinent ot a certain thickness and Width so that it becomes impossible to reload the fuse cartridge with s fuse element of greater than a predetermined cross section. Thus the danger of overloading the circuit is evoided.

In the construction shown in Figure 3, the shell and the end caps or terrules" 3l, 32 are generally like the similar parts shown in Figure l, with the exception that the head of' the ferrule 32 is provided with an opening through which the tuse link 33 er tends,end with a recessed portion to tord access to the holdingscrew 35 by which the adjacent end of the fuse link is attached to the terrule 32. At other end the inse link. is attached directly to the end ot' the csic or ferruie 3l by s screw 3G. The opening in the recessed portion of the cap or terrule 32 through which fuse link extends serves, the disc Qi.. to lirnit or determine tne cross se ot the tuse link used vin connection Wim tridgeu Tension is n link 83 by nie which is hook opening o" able manner. Said spring 37 performs the general `function of the spring 22 before ret'erred to in that it effects a quick separation ot the parts ot the link at the sides of a rupture caused by the fusingot the link.

ln the construction shown in said Figure 3, the shell or cartridge is provided with one or more openings l0 which are covered by it transparent tube 4l made ot mico or like material that is contained Within the. shell. Said openings l0 constitute windows through which the tuse link may be observed to determine whether or not it is intact. The said'niindows may be applied to the other forms or" construction herein shown.

ln the construction shown in Fie-ure 4, the end terminal caps or ierrules 4-5 which slipped over the ends of the shell are provided with centrally recessed or de- 'pressed portions i7 to receive conducting discs 8. between which the i'usc link Li-i is stretched. The depressed heads are cen trellv apertured and the discs El close said "r lires. Seid fuse link is dii'ectiy atied :it one end., as by a screw 50, to one of .ses is connected to the other by means ot a contractile spring` 5l l lsstened st one end to seid link and tisch-eo. :is by e screnv [i2 to the adjacent Seid spring serves to quickly sepa- 't ie parts et the fuse link at 'the sides i s rupture in the sume manner es the s; rings hereto-tore described. Seated within said shell or cartridge 4G. at the sides of the longfitndinai center thereof ere discs 53 which see peripherally tianged to uiiord :1 close seating bearing between the seme and shell. Suid discs 53 are provided with central openings 5e, best shown in Figure 5,- which determine the dimensions of the fuse link extending therethrough.

ln the operation ot the device shown in igure el. When -the fuse is ruptured the parts at the sides of the rupture are separated by the action ot the sprinr 5i and the discs i8 fall away from the heads of the caps or terrules 45.

in the construction shown inligure G, two springs 55 are employed which are directlyconnected at their inner ends to the fuse link 56 and "fastened at their outer ends. as by screws 57, to the heads of the terminal caps or errules 58 that sre applied over the open ends ot the insulating` sheil or cartridge n this construction single disc or partition 6U having' a fuse limiting or determining' openingi'hro'ngh which the fuse extends. is seated within said shell or 'ige The eration the springs to Vuuic 'iy separate the ruptured inse the link and he determining-j i le constructions tne several.

ferred form. Two designs or forms are illustrated in res 7 and 8. The fuse link 65 shown in igure 7 comprises a thin, flat strip that is provided with numerous side notches 66, shown as of V shape to form connecting necks 67 Which determine the load capacity of the fuse.

In Figure 8 the fuse link or strip is provided With a plurality of longitudinally spaced openings 69, shown as made circular, but may be made of other form. In this type of fuse link the effective cross section of the link to carry a current load is the sum of thel Width of the spaces 70 between the openings 69 and the edges of the strip.

These two forms of links, and others of equivalent construction which will be suggested thereby, have the common characteristics of numerous longitudinally and closely spaced, transversely narrow, load determining areas, thus providingr greater safety and incre positive regulation of the fusing temperature, due to any variations Vin the metal, than in other methods. Such numerous closely spaced current determining arcas are especially valuable in connection with a link having means to maintain it unde-r tensile stress and also because a. fuse thus constructed, provided within the fuse chamber with a large number of drop-out sections, as will appear from an inspection of Figures 7 and 8 will permit a section of the fuse to drop-away from two fusing points relative to the inner ends of the outer parts of the broken fuse.

It is to be understood that the feature'of my invention relating to the quick separa- 'tion of the parts of the fuse link at the sides of the rupture may be embodied in fuse structures differing specifically from that herein shown Within the spirit and scope of the invention, as, for instance, to the lowr ampere fuse known as the Edison plug cut out or to the plural type-embodying a number of fuses in a single cartridge.` The invent-ion is not, therefore, limited to the structural details illustrated, except as to the claim wherein such'details are specifically set forth and as imposed by the prior art.

I claim as my invention:

An electrical thermal fuse comprising an open ended shell, conducting ferrules applied thereto. a fuse link attached at one end to one of said ferrules,a bushing within said shell for contact with one of said ferrules, a disc slidable in and filling said bushing, and a spring interposed between said disc and a shoulder on the bushing, said fuse link extending into said bushing, through the spring and through said disc and attached to the disc.

In testimony whereof I claim the foregoing as my invention, I hereunto append my signature at Chicago, Illinois, this 18th day of January, 1918.

BERTRAM J. GRIGSBY. 

